Connection Element Arranged Between a Housing and an Exhaust Pipe

ABSTRACT

A connecting element between a housing and an exhaust pipe, particularly a cone, is characterized in that the connecting element is provided at its interior with at least one guide surface capable of pulsing the exhaust gas flow into rotation.

The invention relates to a connecting element between a housing and anexhaust pipe, particularly a cone.

In exhaust systems, particularly for motor vehicles, one such connectingelement serves to adapt a large flow cross section, such as in theinterior of a housing, to a smaller flow cross section such as in anexhaust pipe. Generally expressed, the connecting element acts like afunnel. The housing concerned may be, for instance, a silencer, ahousing for a catalyst or a housing for a filter.

In modern exhaust systems it is necessary to inject a medium into theexhaust gas flow to produce certain reactions. For example, upstream ofa Diesel particle filter, fuel may be injected so that the particlesretained in the filter are subjected to controlled combustion. In an SCRsystem it may also be provided for that urea is injected to infuseammonia as a means for reducing the nitrous oxides in the exhaust gas,it being generally a requirement that the injected medium is evenlydistributed in the exhaust gas flow for a uniform effect.

Various attempts have been made to distribute the injected mediumuniformly in the exhaust gas. For example, deflectors may be siteddirectly upstream or downstream of the location in the exhaust pipe atwhich the medium is injected so that the exhaust gas is swirled toensure a good distribution of the injected medium. However, engineeringdeflectors in the interior of the exhaust pipe is a problem both asregards the complications in siting them and as regards strengthconsiderations.

The object of the invention is to achieve a good distribution of theinjected medium in the exhaust gas flow with minimum complication andhigh reliability.

For this purpose it is provided for in accordance with the inventionthat the connecting element is provided at its interior with at leastone guide surface capable of pulsing the exhaust gas flow into rotation.The gist of the invention is to swirl the exhaust gas flow as soon as itleaves a housing sited upstream from the location at which the medium isinjected, resulting in good swirling and thus a good distribution of themedium in the exhaust gas flow. The connecting element between thehousing and the exhaust pipe is particularly suitable for this purposesince it is relatively expansive so that it is now much easier, than ina narrow exhaust pipe, to correspondingly engineer swirling the exhaustgas flow.

The guide surface with which the exhaust gas flow is pulsed intorotation may be provided at least one deflector attached to theconnecting element or, preferably, by plastic deformation of the wallsections of the connecting element. This aspect is particularly ofadvantage since no additional components need to be attached in thussimplifying production, whilst eliminating the risk of componentsbecoming detached from the connecting element and damaging othercomponents of the exhaust system.

Preferably the guide surface is formed by at least one helicoidal pathimpressed in the wall of the connecting element. Plastic deformation ofthe wall of the swirler surface area in this way is achievable with fewcomplications.

Advantageous aspects of the invention read from the sub-claims.

The invention will now be described by way of a preferred embodiment asshown in the attached sole drawing depicting diagrammatically a sectionthrough a housing, a connecting element and an attached exhaust pipe.

Shown in the sole FIGURE is a housing 10, in the interior of which asubstrate 12 is arranged, the function of which is immaterial tounderstanding the invention. Instead of the substrate 12 the housing 10could also enclose a silencer.

The housing 10 has a through flow of exhaust gas in the direction of thearrow P. Viewed in the direction of flow the housing 10 is connecteddownstream by a connecting element 14 having the main function ofreducing the flow cross section for the exhaust gas from that of thehousing 10 to that of a exhaust pipe 16 attached downstream to theconnecting element 14.

In the exhaust pipe 16 downstream of the connecting element 14 is aninjector 18 by means of which a medium such as fuel or urea can beinjected into the interior of the exhaust pipe 16 and thus into theexhaust gas flow.

The connecting element 14 in the embodiment as shown is configuredtwo-shelled, i.e. it comprising an outer shell 20 connected via twoflanges 22, 24 to the exhaust pipe 16 and housing 10 respectively.Located within the outer shell 20 is an inner shell 26 shaped so that ahelical pathway 28 is formed circumferentially. The helical pathway 28comprises a helicoidal guide or swirler surface 30 which is orientedmore or less radial to the main direction of flow of the exhaust gas.Since the swirler surface 30 is oriented at an angle to the maindirection of flow of the exhaust gas it pulses the exhaust gas flow intorotation, resulting in a particularly good admixture of the mediuminjected by the injector 18 and the exhaust gas flow.

Since at least the inner shell 26 of the connecting element 14 is madeof sheet metal, the swirler surface 30 can be simply shaped by plasticdeformation of the inner shell 26, particularly by deep drawing. It willreadily be appreciated that the flow response is set by suitablyselecting the pitch of the helical pathway 28. Thus, instead of a singlehelical pathway a multiple helical pathway may be employed which with acorrespondingly larger pitch presents itself in the form of a pluralityof separate swirler surfaces 30 covering a circumferential range of lessthan 360°.

In an aspect different to that as shown, the connecting element may alsobe configured as a single-shell element, the wall of the connectingelement being sufficiently rugged despite the impressed swirler surfaceareas. The fact that the swirler surface is visible to the outside in asingle-shell connecting element is of no detriment to the wantedfunction.

LIST OF REFERENCE NUMERALS

-   -   10 housing    -   12 substrate    -   14 connecting section    -   16 exhaust pipe    -   18 injector    -   20 outer shell    -   22 flange    -   24 flange    -   26 inner shell    -   28 helical pathway    -   30 swirler surface area

1.-8. (canceled)
 9. A connecting element between a housing and anexhaust pipe, the connecting element having at its interior at least oneguide surface formed by plastic deformed wall sections of the connectingelement capable of pulsing the exhaust gas flow into rotation.
 10. Theconnecting element of claim 9, wherein the guide surface, as viewed inthe direction of exhaust gas flow, is oriented at an angle.
 11. Theconnecting element of claim 10, wherein the guide surface is formedhelicoidal.
 12. The connecting element of claim 9, wherein the guidesurface is formed by at least one helical pathway.
 13. The connectingelement of claim 12, wherein the guide surface is oriented radially. 14.The connecting element of claim 9, wherein the connecting element isconfigured multi-walled.
 15. The connecting element of claim 9, whereinthe connecting element is configured as a cone.